High fiving someone in the Sims must make them like you more. So if your character cheats on his wife, her feelings towards you will probably decrease. It must be common among Sims players to exploit the high fiving action and restore her feelings toward the player.

But I've never played, so for all I know they could be high fiving her across her face until she was brainwashed from spousal abuse.

Hopefully that first one. It's the nicer method of resolving adulterous endeavors.